1. Field of the Invention
This invention generally relates to wellbore servicing fluids and methods of servicing a wellbore. More specifically, this invention relates to methods of servicing a wellbore using an aqueous fluid comprising a clay inhibitor.
2. Background of the Invention
Natural resources such as gas, oil, and water residing in a subterranean formation or zone are usually recovered by drilling a wellbore down to the subterranean formation while circulating a drilling fluid (also known as a drilling mud) through the drill pipe and the drill bit and upwardly through the wellbore to the surface. The drilling fluid serves to lubricate the drill bit and carry drill cuttings back to the surface. After the wellbore is drilled to the desired depth, the drill pipe and drill bit are typically withdrawn from the wellbore while the drilling fluid is left in the wellbore to provide hydrostatic pressure on the formation penetrated by the wellbore and thereby prevent formation fluids from flowing into the wellbore. The next operation in completing the wellbore usually involves running a string of pipe, e.g., casing, in the wellbore. Primary cementing is then typically performed whereby a cement slurry is pumped down through the string of pipe and into the annulus between the string of pipe and the walls of the wellbore to allow the cement slurry to set into a hard mass (i.e., sheath), and thereby seal the annulus.
A large percentage of drilled formations are comprised of argillaceous formations like shales. Shales refer to a loosely defined heterogeneous argillaceous material ranging from clay-rich gumbo to shale siltstone, with extremely low permeability and containing clay minerals. When drilling and cementing with water-based fluids under an overbalanced condition in a shale formation without an effective flow barrier present at the wellbore wall, wellbore servicing fluid pressure will penetrate progressively into the formation. Because of the saturation and low permeability of a shale formation, penetration of a small volume of filtrate into the formation can result in a considerable increase in pore fluid pressure near the wellbore wall. The increase in pore fluid pressure can reduce the effective cement support, which leads to a less stable wellbore condition.
Therefore, a need exists for wellbore servicing fluids that reduce water absorption in subterranean formations comprised of argillaceous material. There also exists a need for a method of servicing a wellbore having argillaceous formations using an aqueous servicing fluid.